💿🐜 Antkeeper source code
https://antkeeper.com
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111 lines
3.3 KiB
111 lines
3.3 KiB
/*
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* Copyright (C) 2020 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "mesh-functions.hpp"
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#include "math/math.hpp"
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#include <unordered_map>
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struct edge_hasher
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{
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std::size_t operator()(const std::array<std::size_t, 2>& v) const noexcept
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{
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std::size_t hash = std::hash<std::size_t>()(v[0]);
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return hash ^ (std::hash<std::size_t>()(v[1]) + 0x9e3779b9 + (hash << 6) + (hash >> 2));
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}
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};
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void create_triangle_mesh(mesh& mesh, const std::vector<float3>& vertices, const std::vector<std::array<std::uint_fast32_t, 3>>& triangles)
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{
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for (const auto& vertex: vertices)
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mesh.add_vertex(vertex);
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std::unordered_map<std::array<std::size_t, 2>, ::mesh::edge*, edge_hasher> edge_map;
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const std::vector<mesh::vertex*>& mesh_vertices = mesh.get_vertices();
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std::vector<::mesh::edge*> loop(3);
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for (const auto& triangle: triangles)
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{
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::mesh::vertex* triangle_vertices[3] =
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{
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mesh_vertices[triangle[0]],
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mesh_vertices[triangle[1]],
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mesh_vertices[triangle[2]]
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};
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for (int j = 0; j < 3; ++j)
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{
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::mesh::vertex* start = triangle_vertices[j];
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::mesh::vertex* end = triangle_vertices[(j + 1) % 3];
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if (auto it = edge_map.find({start->index, end->index}); it != edge_map.end())
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{
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loop[j] = it->second;
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}
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else
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{
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loop[j] = mesh.add_edge(start, end);
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edge_map[{start->index, end->index}] = loop[j];
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edge_map[{end->index, start->index}] = loop[j]->symmetric;
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}
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}
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mesh.add_face(loop);
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}
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}
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void calculate_face_normals(float* normals, const mesh& mesh)
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{
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const std::vector<mesh::face*>& faces = mesh.get_faces();
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for (std::size_t i = 0; i < faces.size(); ++i)
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{
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const mesh::face& face = *(faces[i]);
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float3& normal = reinterpret_cast<float3&>(normals[i * 3]);
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const float3& a = reinterpret_cast<const float3&>(face.edge->vertex->position);
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const float3& b = reinterpret_cast<const float3&>(face.edge->next->vertex->position);
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const float3& c = reinterpret_cast<const float3&>(face.edge->previous->vertex->position);
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normal = math::normalize(math::cross(b - a, c - a));
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}
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}
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aabb<float> calculate_bounds(const mesh& mesh)
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{
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float3 bounds_min;
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float3 bounds_max;
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for (int i = 0; i < 3; ++i)
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{
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bounds_min[i] = std::numeric_limits<float>::infinity();
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bounds_max[i] = -std::numeric_limits<float>::infinity();
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}
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for (const mesh::vertex* vertex: mesh.get_vertices())
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{
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const auto& position = vertex->position;
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for (int i = 0; i < 3; ++i)
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{
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bounds_min[i] = std::min<float>(bounds_min[i], position[i]);
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bounds_max[i] = std::max<float>(bounds_max[i], position[i]);
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}
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}
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return aabb<float>{bounds_min, bounds_max};
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}
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